1. Field of the Invention
The present invention relates to wastewater treatment plants or systems and, more particularly, to a 3-compartment vessel for use in such plants.
2. Description of Prior Art
In U.S. Pat. No. 6,406,619 ('619 patent) there is disclosed a three compartment vessel for use in waste water treatment systems. The vessel disclosed in the '619 patent comprises a centrally located, generally cylindrical vessel and two end tanks attached to the central, cylindrical vessel. The two end tanks are crescent shaped when viewed in top plan view. In the system disclosed in the '619 patent, one of the end tanks is a pretreatment tank into which the raw waste stream is introduced. The center, cylindrical vessel is an aerobic treatment tank. The fluid from the pretreatment tank, from which a majority of the solids have settled, flows into the aerobic treatment tank wherein it is treated with an oxygen-containing gas in the well-known manner so that the bacteria can aerobically digest the remaining solids. The clarified water from the center, aerobic tank then flows into a post treatment tank, commonly referred to as a pump tank, from which the water can then be dispensed, i.e., for irrigation, or if properly chlorinated, into certain streams, etc. As noted in the '619 patent, the center, cylindrical tank is the largest of the three and can contain a volume of from 800 to 1,400 gallons of liquid, the preferred embodiment holding roughly 1,000 gallons of liquid. The two end tanks, i.e., the pretreatment and post-treatment tanks, as disclosed in the '619 patent are smaller and typically range in size from 300 to 1,000 gallons, and in the preferred embodiment the pretreatment tank holds 400 gallons while the post-treatment tank holds 750 gallons.